Leggiest Animal Thrives Near Silicon Valley

Below:

Next story in Science

The world's leggiest animal features up to 750 legs and may make
its own silk "clothing."

The translucent species, Illacme plenipes, meaning "in
highest fulfillment of feet," lives in the foggy, oak-forested
outskirts of Silicon Valley, just south of San Francisco. Females
of this millipede have a leg up over males, which possess a mere
562 limbs. That's still impressive, as most common garden
millipedes have about 100 legs.

Paul Marek, a University of Arizona entomologist, told Discovery
News that "all the legs evolved for burrowing in its deep
subterranean habitat, and for clinging to the sandstone
boulders."

Marek and colleagues also found that the ultra-leggy millipede
possesses body hairs that produce silk.

"We suggest that the silk may have evolved as a defense secretion
or a means to keep their exoskeleton clean from parasites and
little bits of junk that might accumulate on them in their
subterranean habitat," Marek said.

This exoskeleton is jagged, scaly and translucent. He explained
that many subterranean creatures, particularly those that live in
caves, are de-pigmented and are translucent and/or white. It is
energetically costly to produce pigment, and these animals do not
need to maintain body coloration.

The millipede sports comparatively massive antennae that are used
to feel its way through the dark because it lacks eyes. Its
mouth, unlike other millipedes that chew with developed grinding
mouthparts, is rudimentary. The scientists believe that its lower
jaw swings down, allowing the sharp and pointy mandibles to
pierce plant or fungal material.

"Once the plant/fungal material is pierced and exuding juices,
the millipede sucks up the fluid through its tooth-lined labral
opening," Marek said.

He continued, "Nearly all millipedes are decomposers and feed on
decaying organic matter. They're an essential part of the
ecosystem; they breakdown organic matter and release nutrients
(like carbon, nitrogen and sugars) for future generations of life
to use."

The closest presumed relative of the millipede is
Nematozonium filum, which lives in South Africa. The
common ancestor of N. filum and I. plenipes was
able to spread to present-day California prior to the
supercontinent of Pangaea breaking apart around 200 million years
ago.

"Over millions of years, and through evolutionary time, the
millipede became specially adapted to this unique area in
California," Marek said. "It's known as a relict species because
it is isolated both in space and evolutionary time. Because of
this, and significant development (climate change, transit,
housing and other human industry), the species is certainly in
danger of further habitat loss and potentially extinction."

The leggy animal's habitat is also home to other unique animals
and plants, which include local flowers, trees, ferns, mosses,
salamanders, scorpions, beetles and trapdoor spiders. Many of
them are found no place else on Earth.

Casey Richart, a San Diego State University evolutionary
biologist, agrees the leggy millipede "appears to be
micro-endemic and should be of conservation concern. The
importance of this species is potentially very high. Since it has
diverged so anciently from its nearest relative, it likely has
unique chemical compounds, some of which may have utility to
human society."

Richart also wondered if the millipede could be the leggiest
animal ever- past or present. As of now, no other known extinct
or living animal has had more than 750 legs.

The millipede is described by Marek and colleagues, Jason Bond of
Auburn University and William Shear of Hampden-Sydney College, in
the latest issue of the journal ZooKeys.